Focus detecting apparatus including ray orientation changes

ABSTRACT

A focus detecting apparatus includes a plurality focus detecting zones arranged in a first orientation configuration. A plurality of condenser lenses are disposed behind the zones, each of the condenser lenses corresponding to each of the focus detecting zones. The apparatus further includes plural pairs of separator lenses for splitting images seen through the zones. A sensor unit having multiple line sensors is arranged in a second orientation configuration that differs from the first orientation configuration. The multiple line sensors are disposed on a reimaging plane for reimaging the split images, and each of the line sensors corresponds to each of the multiple focus detecting zones. The apparatus also includes a mechanism for deflecting a bundle of rays, passing through at least one of the plurality focus detecting zones, to be close to another bundle of rays passing through another focus detecting zone while the first configuration orientation is maintained. A mechanism for changing the orientation of the bundles of rays passing through the plural focus detecting zones of the first orientation configuration into the second orientation configuration, is provided and is disposed between the deflecting mechanism and the separator lenses.

This application is a continuation, of application Ser. No. 08/272,050,filed Jul. 8, 1994, now U.S. Pat. No. 5,530,236.

This application is related to application Ser. No. 085,137, filed onJul. 2, 1993, now U.S. Pat. No. 5,321,248, and continuation applicationSer. No. 187,066, filed on Jan. 27, 1994, now U.S. Pat. No. 5,397,887and based upon the application Ser. No. 085,137, disclosures of whichare expressly incorporated herein in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a focus detecting apparatus, whichattains an improved arrangement of light receiving portions (CCDline-sensors: AF sensors) on a reimaging plane and openings formed on afield mask, which is disposed in front of a reimaging optical system toeliminate unnecessary light. Thus, the openings, hereinafter designatedas apertures, are accordingly formed as an area through which onlynecessary bundles of rays for reimaging are passed to be incident on thelight receiving portions.

2. Description of Related Art

A focus detecting apparatus, which is related to the present invention,has been disclosed in the Japanese Laid-Open Patent Publications No.01-155308 and No. 02-58012. The focus detecting apparatus in thesepublications works in the following manner an image seen through anaperture regarding a field mask is separated by a pair of separatorlenses and reimaged on AF sensors so that a focus state is judged by thephase difference of the output of the AF sensors.

On the other hand, the focus detecting apparatus mentioned above hassome drawbacks on the arrangement of the apertures and the AF sensors.The arrangement of the AF sensors has been the same as that of theapertures on the field mask. For example, if the apertures are arrangedin "H" shape on the field mask, the AF sensors are arranged in "H" shapeon the reimaging plane. Each arrangement of the apertures and the AFsensors may not cause any functional problems. It should, however, benoted that preferable conditions required for the apertures on the fieldmask and for the AF sensors are inherently different.

For the apertures, in particular, those formed away from an optical axisof a photographing lens, to minimize an adverse effect of vignetting, itis more preferable for them to be formed in the sagital direction of thephotographing lens, i.e., a longer side of the aperture is placed alonga shorter side of a film plane, rather than along a longer side of thefilm plane.

On the other hand, for the AF sensors serving as the light receivingportions, it is preferable that the AF sensors are disposed, withoutregard to the arrangement of the apertures, in a manner that an areaoccupied by the AF sensors is as small as possible, for the purpose ofspace saving in a camera.

If the AF sensors are aligned in a single straight line with a space ofminimum necessity, the size of a module in which a reimage formingoptical system is contained can be much smaller.

Still further, as position and diameter of an exit pupil of aphotographing lens vary due to zooming or due to a type of lens beingattached to a camera, a pupil of the focus detecting system may suffer avignetting thus, it is preferable that an aperture formed on aperipheral part of the field mask receives a bundle of rays from an areaof the exit pupil of the photographing lens closer to the optical axisof the lens.

SUMMARY OF THE INVENTION

The primary object of the present invention is to provide a focusdetecting apparatus in which bundles of rays can be incident on thelight receiving portions (AF sensors) in a manner that at least onebundle of ray is made closer to another bundle of rays. In the lightreceiving portions, segments (of the light receiving portions)corresponding to each of the apertures can therefore be set closely,which contributes to making the total width of the light receivingportions shorter, and enabling the focus detecting apparatus to bedownsized.

Moreover, the present invention is designed to provide a focus detectingapparatus which enables the apertures on the field mask to receive abundle of rays from an area of the exit pupil of the photographing lenscloser to the optical axis of the lens.

In order to accomplish the above object in a practice, the focusdetecting apparatus includes a field mask disposed on an equivalentfocal plane, the field mask being provided with multiple aperturesarranged in a first orientation configuration; a plurality of condenserlenses disposed behind the apertures, each of the condenser lensescorresponding to each of the apertures; and plural pairs of separaterlenses for splitting images seen through the apertures. The focusdetecting apparatus also includes a sensor unit having multiple linesensors arranged in a second orientation configuration that differs fromthe first orientation configuration, the multiple line sensors beingdisposed on a reimaging plane for reimaging the split images, and eachof the multiple line sensors corresponding to each of the multipleapertures. Further, the focusing detecting apparatus is provided with amechanism for deflecting a bundle of rays passing through at least oneof the multiple apertures to be close to another bundle of rays passingthrough another aperture while the first orientation configuration ismaintained. Still further, a mechanism for changing orientation of thebundles of rays of the first orientation configuration passing throughthe multiple detecting zones into the second orientation configurationis provided; the changing mechanism is disposed between the deflectingmechanism the separater lenses.

The present invention relates to the subject matter contained in theJapanese Patent Application No. 5-169082 (filed on Jul. 8, 1993) whichis expressly incorporated by reference in their entirety.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described below in detail with reference to theaccompanying drawings, in which;

FIG. 1 is a perspective view of the focus detecting apparatus to whichthe present invention is applied;

FIG. 2 is a perspective view of the reimage forming optical systemcontained in one module;

FIG. 3 is a exploded view showing a detail of the reimage formingoptical system of FIG. 2;

FIG. 4 is a plane view indicating the effect of deflection by thecondenser lens of the peripheral AF detecting zone;

FIG. 5(a) is the original arrangement of the apertures, condenserlenses, separator lenses, and the light receiving portions (AF sensors)without considering the deflecting means;

FIG. 5(b) is an example wherein the distance between the light receivingportions is made shorter, and no deflecting means is considered;

FIG. 5(c) is an example of the deflecting means (prism) by which adirection of bundle of a rays passed through the aperture formed in asagittal direction of the photographing lens is the same as that of FIG.5(a);

FIG. 5(d) is another example of the deflecting means (eccentricity ofcondenser lens) by which a direction of a bundle of rays passed throughthe aperture formed in the sagittal direction of the photographing isthe same as that of FIG. 5(a);

FIG. 6(a) is the original arrangement of the apertures, condenserlenses, separeter lenses, and the light receiving portions (AF sensors)without considering the deflecting means;

FIG. 6(b) is an example wherein the distance between the light receivingportions is made longer to receive a bundle of rays, passed through theaperture formed in the sagital direction of the photographing, from anarea, of the exit pupil of the photographing lens, closer to the opticalaxis of the photographing lens;

FIG. 6(c) is an example of the deflecting means (prism) by which thebundle of ray received by the aperture formed in the sagittal directionof the photographing is inclined toward the optical axis of thephotographing lens as in FIG. 6(b), and the distance between the lightreceiving portions are as the same as that of FIG. 6(a);

FIG. 6(d) is another example of the deflecting means (eccentricity ofcondenser lens) by which a bundle of rays received by an aperture formedin the sagittal direction of the photographing lens is inclined towardsthe optical axis of the photographing lens as in FIG. 6(b), and thedistance between the light receiving portions is as the same as that ofFIG. 6(a);

FIG. 6(e) is still another example of the deflecting means (prism) bywhich the bundle of rays received by the aperture formed in the sagittaldirection of the photographing lens is inclined toward the optical axisof the photographing lens as in FIG. 6(b), and the distance between thelight receiving portions is shorter than that of FIG. 6(a);

FIG. 7(a) is an example of the deflecting means (prism) by which thebundle of ray received by the aperture formed in the radial direction ofthe photographing lens is inclined towards the bundle of rays passedthrough the aperture formed in the sagittal direction, while the bundleof rays received by the aperture formed in the sagittal direction isinclined toward the optical axis of the photographing lens;

FIG. 7(b) is another example of the deflecting means (prisms) by whichthe bundle of rays received by the aperture formed in the radialdirection of the photographing lens is inclined more toward AF sensorscorresponding to the aperture formed in the sagittal direction of thephotographing lens, while the bundle of ray received by the apertureformed in the sagittal direction is made inclined toward the opticalaxis of the photographing lens;

FIG. 8 is a front view of the field mask for another type of focusdetecting apparatus;

FIG. 9 is a perspective view of the focus detecting apparatus of anthertype to which the present invention is applied;

FIG. 10 is a perspective view of the focus detecting apparatus withoutthe deflecting means;

FIG. 11(a) is the original arrangement of the intermediate and theperipheral apertures formed in the sagittal direction, includingcondenser lenses, separator lenses, and the light receiving portions (AFsensors) without considering the deflecting means;

FIG. 11(b) is an example of the deflecting means wherein bundles of rayspassing through the intermediate and the peripheral apertures areinclined toward the optical axis of the photographing lens by disposingthe light receiving portions distant from the optical axis of thephotographing lens;

FIG. 11(c) is an example of the deflecting means (prisms) in which thedirection of the bundles of rays received by the intermediate and theperipheral apertures formed in the sagittal direction are inclinedtoward the optical axis of the photographing lens without disposing thelight receiving portions far from the optical axis of the photographinglens;

FIG. 12(a) is an example wherein the light receiving portions for theintermediate and the peripheral apertures are closely disposed withoutconsidering the deflecting means, and the bundle of rays passed throughthe intermediate aperture is inclined too much toward the optical axisof the photographing lens;

FIG. 12(b) is another example of the deflecting means (prism) by whichthe light receiving portions for the intermediate and the peripheralapertures are disposed closely while the direction of the bundles ofrays received in the intermediate and the peripheral apertures aremaintained as FIG. 11(b) and FIG. 11(c).

FIG. 12(c) is still another example of the deflecting means (prisms) bywhich the light receiving portions for the intermediate and theperipheral apertures are disposed closely while the direction of thebundles of rays received in the intermediate and the peripheralapertures are maintained as in FIG. 11(b) and FIG. 11(c).

PREFERRED EMBODIMENTS OF THE INVENTION

A focus detecting apparatus to which the present invention is applied isexplained, according to FIG. 1, as a focus detecting apparatus providedin a single lens reflex camera. The focus detecting apparatus in generalis disposed in the single lens reflex camera so that a bundle of rayspassing through a photographing lens and a main mirror (a quick returnmirror), reflected by a submirror, is finally made incident on the AFsensors included in a reimaging optical system. Along a path of thebundle of rays, in front of the reimaging optical system, a field mask10 is provided. The field mask 10 is substantially disposed at anequivalent focal plane on which an image of an object is formed by thephotographing lens. On the field mask 10, three apertures 11, 12, 13,through which the bundle of rays pass, are formed in a "H" shape. As theapertures are formed for the purpose of eliminating unnecessary lightwhich should not be used for reimaging, an area of the aperture is equalto or slightly larger than that of the light receiving portions of theAF sensors. In the embodiments, this "H" shape arrangement of theapertures is designated as a first orientation configuration.

The equivalent focal plane, on which an image through the photographinglens is formed, is optically conjugate with the film surface for asilver-salt camera, and also conjugate with image sensors for anelectronic still camera. Furthermore, for a single lens reflex camera,the equivalent focal plane is optically conjugate with a focusing screenprovided in a view finder as well as with the film surface.

The central aperture 11 is formed so that an optical axis of thephotographing lens meets the center of figure of the aperture 11. It isdefined that the central aperture 11 is disposed along a radialdirection of the photographing lens. The apertures 12 and 13 are formedat both sides of the aperture 11. In particular, the longer side of theperipheral apertures are formed to be normal to the longer side of thecentral aperture 11, i.e., the apertures 12 and 13 are formed in asagittal direction of the photographing lens. The first orientationconfiguration, as stated above, is consequently the "H" shape.

In addition to the apertures 11, 12, and 13, the outline of a reimagingsystem is explained. In FIG. 1, the central aperture 11 corresponds to areimaging optical system "A" which includes a first mirror 20, a pair ofseparator lenses 30, 31, and a central light receiving portion 41 of theAF sensors 40a disposed on a reimaging plane 40.

Likewise, the aperture 12, formed in the sagittal direction of thephotographing lens, corresponds to a reimaging system "B" which includesa second mirror 21 and a third mirror 22, a pair of separator lenses 32and 33, and a peripheral light receiving portion 42 of the AF sensor40a.

The structure of the reimaging optical system "B" is also applied to areimaging system "C" i.e., the second mirror 21 and the third mirror 22,a pair of separator lenses 34 and 35, and a peripheral light receivingportion 43 of the AF sensor 40a.

A focus detecting apparatus of this type receives a bundle of raysrepresenting an object passing through an exit pupil of thephotographing lens into an aperture on a field mask on which an image bythe photographing lens is formed. In FIG. 1, four circles E1, E2, E3,and E4 in an exit pupil E of the photographing lens indicate areas onthe exit pupil E seen from the light receiving portions 41, 42, and 43of the AF sensors 40a. The AF sensors are a single CCD sensors, andpredetermined segments of the single CCD sensors are used as the lightreceiving portions 41, 42, and 43. It should be noted that thesesegments are not actual cut portions of the CCD sensors, but areelectrically determined segments a used as light receiving portions.

In a more detailed manner, the separator lenses 30 and 31 canrespectively see the object to be photographed through the areas of E1and E2 through the central aperture 11. The bundle of rays from theareas E1 and E2 are deflected 90 degrees (a right angle) by the mirror20 toward the separator lenses 30 and 31 and then , the bundles of raysare separated by the separator lenses 30 and 31. The separated bundle ofrays are respectively led to the central light receiving portion 41 ofthe AF sensors 40a to reimage the object seen through the centralaperture 11; and therefore pupils of the separator lenses 30 and 31 areoptically conjugate with the exit pupil E of the photographing lens.

Similar to the reimaging optical system "A" in the reimaging opticalsystem "B" the separator lens pair 32 and 33 can respectively see theobject to be photographed through the areas of E3 and E4 through theaperture 12 formed in the sagittal direction. The bundle of rays fromthe areas E3 and E4 are deflected 90 degrees (a right angle) by themirror 21 and deflected 90 degrees (a right angle) by the mirror 22toward the separator lenses 32 and 33, and then the bundle of rays areseparated by the separator lenses 32 and 33. The separated bundle ofrays are respectively led to the peripheral light receiving portion 42of the AF sensors 40a to reimage the object seen through the aperture12.

Like the reimaging optical system "B" in the reimaging optical system"C" the separator lens pair 34 and 35 can respectively see the object tobe photographed through the areas of E3 and E4 through the aperture 13formed in the sagittal direction. The bundle of rays from the areas E3and E4 are deflected 90 degrees (a right angle) by the mirror 21 andalso deflected 90 degrees (a right angle) by the mirror 22 toward theseparator lenses 34 and 35, and then the bundle of rays are separated bythe separator lenses 34 and 35. The separated bundle of rays arerespectively led to the peripheral light receiving portion 43 of the AFsensors 40a to reimage the object seen through the aperture 13 formed inthe sagittal direction.

As shown in FIG. 1, the light receiving portions 41, 42, and 43 of theAF sensors 40a are disposed on the reimaging plane 40 in a "" shape.This "" shape is designated as a second orientation configuration, whichis different form the "H" shape of the first orientation configurationformed by the apertures 11, 12, and 13.

In a view finder (not shown), there are provided AF focusing zonescorresponding to each of the apertures 11, 12, and 13. On the otherhand, a focus detecting circuit (not shown) detects a focusing conditionby an output of an AF sensor corresponding to the aperture being used,or by an output of AF sensor corresponding to an aperture, which meetsan object selected by a circuit in the camera body.

As explained, the mirrors 20, 21, and 22 allow a different orientationconfiguration of the AF sensors 40a without following the firstorientation configuration of the apertures 11, 12, and 13, because thesemirrors deflect the bundle of rays, passed through the apertures 11, 12,and 13 having the first orientation configuration, 90 degrees (a rightangle) to the AF sensors 40a with the second orientation configuration.The mirrors 20, 21, and 22 function as an orientation changing means.

In FIG. 2 and FIG. 3, structural components of the reimaging opticalsystem are shown. The components shown in FIG. 2 are fabricated in asingle module, and placed in the camera. Behind the field mask 10,condenser lenses 61, 62, and 63 functioning as relay lenses are providedto correspond to each of the AF detecting zones 11, 12, and 13.Furthermore, a collection lens group 70 comprising auxiliary lenses 71,72, and 73, a separator lens group 30a comprising separator lenses 30through 35, and the CCD line sensors 40a are disposed in this order.

As shown in FIG. 3, an optical axis (shown by a dotted line), of thecondenser lens 61, corresponding to the central aperture 11, is alignedto a central axis of the separator lenses 30 and 31, and an optical axisof the auxiliary lens 71. On the other hand, optical axes "x--x" and"y--y" of the condenser lenses 62 and 63 corresponding to the apertures12 and 13 respectively are deviated toward the condenser lens 61 todeflect the bundles of rays passed through the condenser lenses 62 and63 toward the condenser lens 61. In other words, by eccentricallydisposing the condenser lenses 62 and 63 from the optical axes of thecondenser lens 62 and 63 toward the optical axis of the condenser lens61; it is understood that the condenser lenses 62 and 63 function asprisms.

Effects of the deviation of the condenser lenses 62 and 63 are shown inFIG. 4. FIG. 4 shows the above mentioned deviation of the condenser lens62 in relation to the bundle of rays respectively taken in the aperture12 formed in the sagittal direction of the photographing lens and theaperture 11 formed in the radial direction of the photographing lens. Itcan be understood from FIG. 4 that by eccentrically disposing thecondenser lenses 62 and 63, the bundles of rays passed through theapertures 12 and 13 are made to be close to the bundle of ray passedthrough the aperture 11. In other words, the eccentricity of thecondenser lenses 62 and 63 constitutes a deflecting means to deflect atleast one bundle of ray heading for the reimaging plane, toward thebundle of ray passed through the condenser lens and, also heading forthe reimaging plane.

It should be noted that the deflecting means can therefore attain apreferable arrangement of the light receiving portions 41, 42, and 43 ofthe AF sensors 40a, because the light receiving portions 41, 42, and 43of the AF sensors 40a on the reimaging plane 40 can be disposed as closeas possible within a range were no interference of light occurs, so thatthe total length of the second orientation configuration can actually beshortened. In particular, when the AF sensors 40a comprises the singleCCD sensors, in accordance with the above-described functioning of thedeflecting means, a distance between the segments (electricallydetermined and used as the light receiving portions) can be shortened.Moreover, when the minimum distance without any interference of light isknown, the total length of the single CCD line sensors can be minimizedfor the purpose of saving space.

The deflecting mechanism as it relates to the present invention, isexplained according to FIG. 5(a) through FIG. 5(d), FIG. 6(a) throughFIG. 6(e), and FIG. 7(a) and FIG. 7(b). For better understanding of thedeflecting mechanism, the drawings show only the two apertures 11 and12, and the corresponding light receiving portions 41 and 42 of the AFsensors 42a in exploded views. Moreover, in these figures, the functionof the orientation changing mechanism i.e. mirror 20, 21, and 22, isdisregarded. A series of measures applied to the aperture 12 is alsoapplicable to the aperture 13. Effects of the above measures for theaperture 12 are also obtainable for the aperture 13.

Suppose an arrangement of the apertures 11 and 12, the condenser lenses61 and 62, the separater lenses 30, 31, 32, and 33 and the lightreceiving portions 41 and 42 of the AF sensors 42a, shown in FIG. 5(a),is the original arrangement in which no consideration is given to thelocation of the light receiving portions 41 and 42 of the AF sensors42a. In other words, the light receiving portions 41 and 42 are disposedwith a distance "d," which simply follows the distance between thepositions of the apertures 11 and 12.

With the arrangement of FIG. 5(a), if only the distance "d" isshortened, as shown in FIG. 5(b), the direction of the bundle of raystaken in the aperture 12 is largely deviated from the original course ofFIG. 5(a), so that either one or both light receiving portions 41 and 42of the AF sensors may suffer a vignetting. Enough light may consequentlynot be led to the light receiving portions 41 and 42. To compensate forthe above drawback in FIG. 5(b), a prism 80 is disposed between thecondenser 62 and the separater lenses 32 and 33 as shown in FIG. 5(c),so that the direction of the bundle of ray taken in the aperture 12 canbe maintained as that of FIG. 5(a) while the distance "d" is madeshorter than that of FIG. 5(a).

The same effect of FIG. 5(c) can be obtained by utilizing aneccentricity of the condenser lens 62. In other words, as shown in FIG.5(d), the condenser lens 62 is deviated toward the condenser lens 61. Itis understood that the condenser lens 62 in FIG. 5(d) functions as aprism.

As explained, the prism 80 and the eccentricity of the condenser lens 62function as the deflecting mechanism having a feature that the directionof the bundles of rays to the condenser lenses 61 and 62 is not changedwhile the light receiving portions 41 and 42 of the AF sensors aredisposed closer.

The above examples of FIG. 5(a) through FIG. 5(d) mainly deal with thearrangement of the light receiving portions of the AF sensors.Meanwhile, when an image is formed through the apertures 12 and 13formed in the sagittal direction of the photographing lens, it ispreferable that the aperture 12, for example, receive in a bundle ofrays from an area of the exit pupil E as close as possible to theoptical axis of the photographing lens, because a bundle of rays takenfrom the peripheral part of the photographing lens may cause vignettingif the size of the exit pupil of the photographing lens is small, and/orwhen the exit pupil of the photographing lens moves in the optical axisdirection. It Is therefore preferable that the direction of the bundleof rays be made to incline toward the optical axis of the photographinglens.

Examples, which take the above consideration into account, are shown inFIG. 6(a) through FIG. 6(e). Similar to FIG. 5(a), the originalarrangement of the apertures 11 and 12, the condenser lenses 61 and 62,the separator lenses 30, 31, 32, and 33 is shown in FIG. 6(a).

If the distance "d" of the light receiving portions 41 and 42 of the AFsensors is made longer, as shown in FIG. 6(b), to enable the peripheralAF detecting zone 12 to receive a bundle of ray from an area on the exitpupil E of the photographing lens close to the optical axis of thephotographing lens, a space for containing the light receiving portions41 and 42 of the AF sensors is large, which means that the size of themodule is inevitably large.

To compensate for the above drawback, the prism 80, as shown in FIG.6(c), is disposed between the condenser lens 62 and the separater lenses32 and 33. It is clearly shown in FIG. 6(c) that the distance "d" ismaintained as the same as that of FIG. 6(a) while the bundle of rays ismade to incline toward the optical axis of the photographing lens.

The same effect is also obtained by utilizing an eccentricity of thecondenser lens 62. In other words, as shown in FIG. 5(d), the condenserlens 62 is deviated toward the condenser lens 61. In addition, if aprism 81 with strong refraction power is employed, as shown in FIG.6(e), the aperture 12 can take in the bundle of ray from an area on theexit pupil E close to the optical axis of the photographing lens, i.e.,the distance between the light receiving portions 41 and 42 of the AFsensors can be shortened. It is understood that both effects, shown inFIG. 5(c) and that of FIG. 6(c), are attained at the same time.

The eccentricity of the condenser lens 62 and the prism 80 in FIG. 6(a)through FIG. 6(e) also function as the deflecting mechanism.

FIG. 5(a) through FIG. 5(d) and FIG. 6(a) through FIG. 6(e) mainly dealwith the reimage forming optical systems "B" and/or "C" which correspondto the apertures 12 and 13 formed in the sagittal direction of thephotographing lens. On the other hand, FIG. 7(a) and FIG. (b) show thatthe same space saving effect can be obtained even in the reimagingoptical system "A", which corresponds to the aperture 11 formed in theradial direction of the photographing lens, with maintaining the bundleof ray taken in the aperture 12 being inclined toward the optical axisof the photographing lens.

In FIG. 7(a), the prism 81 with strong refraction power is disposedbetween the condenser lens 61 and the separater lens 30 and 31, so thatthe bundle of rays passed through the aperture 11 can be close to thebundle of rays passed through the aperture 12.

In FIG. 7(b), in addition to the arrangement of the prism 81 asdescribed above, the prism 80 with weak refractive power may be disposedbetween the condenser lens 62 and the separater lenses 32 and 33, sothat the distance between the light receiving portions 41 and 42 of theAF sensors 40a is closer than that of FIG. 7(a). The prism 80 and theprism 81 function as the deflecting mechanisms.

Another embodiment is explained with reference to FIG. 8 and FIG. 9. Itis noted that components, which are same as those of FIG. 1 and FIG. 2,have the same reference numerals. In these drawings, six apertures andcorresponding reimaging optical systems are shown. Apertures 11 and 16are arranged in the radial direction of the photographing lens, anddisposed around the center of the field mask 10. Apertures 12 and 13,are arranged in the sagittal direction of the photographing lens anddisposed in the vicinity of the peripheral areas of the field mask 10.An intermediate aperture 14, is arranged in the sagittal direction ofthe photographing lens, and disposed between the peripheral aperture 12and the central aperture 11 and 16. An intermediate aperture 15 isformed in the sagittal direction of the photographing lens and disposedbetween the peripheral aperture 13 and the central apertures 11 and 16.The peripheral and the intermediate apertures 12, 13, and 14, 15, inparticular, can receive bundle of rays representing an image even when aheight of the image becomes taller around the peripheral andintermediate areas of the field mask 10.

Each of the above apertures 11 through 16 correspond to reimagingoptical systems A' to C'. The reimaging optical system A' includes amirror 20, an integral pair of condenser lenses 61 and 64, integralpairs of four separater lenses 30, 31, and 30', 31', and central lightreceiving portions 41 and 44 of the AF sensors 40a.

The reimaging optical system B', which actually covers the peripheralaperture 12 and the intermediate aperture 14, includes mirrors 21 and22, a condenser lens 63 for the intermediate aperture 14, a condenserlens 66 for the peripheral aperture 12, integral pairs of four separaterlenses 34, 35, and 34', 35', a light receiving portion 43 for theintermediate aperture 14, and a light receiving portion 46 for theperipheral aperture 12. The reimaging optical system C', which actuallycovers the peripheral aperture 13 and the intermediate aperture 15,includes mirrors 21 and 22, a condenser lens 62 for the intermediateaperture 15, a condenser lens 65 for the peripheral aperture 13,integral pairs of four separater lenses 32, 33, and 32', 33', a lightreceiving portion 42 for the intermediate aperture 15, and a lightreceiving portion 45 for the peripheral aperture 15. With the reimagingoptical system A', for example, the bundle of rays passed through thecentral AF aperture 11 is incident on the condenser lens 61corresponding to a normal height of an image. Then the bundle of raysfrom the condenser lens 61 is reflected 90 degrees (a right angle) bythe mirror 20 toward the separater lenses 30 and 31 to split the imagerepresented by the bundle of rays through the condenser lens 61. Thesplit images are formed on the light receiving portion 41 on thereimaging plane 40. Similar to the central aperture 11, the condenserlens 64 receives a bundle of rays passed through the central aperture 16when a height of an image is taller, and the bundle of ray through thecondenser lens 64 is reflected 90 degrees (a right angle) by the mirror20. The bundle of rays is directed toward the separater lenses 30' and31' to split the image represented by the bundle of rays through thecondenser lens 64, and then the split images are formed on the lightreceiving portion 44 of the AF sensors 40a on the reimage forming plane40.

When a height of an image becomes taller at the intermediate aperture 15and the peripheral aperture 13, the condenser lenses 62, 65, the mirrors21 and 22, the separater lenses 32, 33, 32', 33', and the lightreceiving portions 42 and 45 work as those of the reimaging opticalsystem A' do.

When a height of an image becomes taller at the intermediate aperture 14and the peripheral aperture 12, the condenser lenses 63, 66, the mirrors21 and 22, the separater lenses 34, 35, 34', 35'and the light receivingportions 43 and 46 work as those of the reimaging optical system A' do.

In particular, the condenser lenses 62 and 63 can function as thedeflecting means by providing eccentricity to the lens, as shown in FIG.9, or attaching another prism (not shown), so that the bundle of rayspassed through each of the condenser lenses 62 and 63 are closer,respectively to the bundles of rays passed through each of the condenserlenses 65 and 66 corresponding to the peripheral apertures 12 and 13.For example when, the bundle of rays which are passed through thecondenser lenses 62 and 63, respectively are reflected 90 degrees (aright angle) by the mirror 21 and reflected 90 degrees (a right angle)by the mirror 22, these bundles of rays are made closer to the bundlesof rays passing through the condenser lenses 65 and 66, respectivelybecause the bundles of rays passing through the condenser lenses 62 and63 are already deflected due to the eccentricity of the condenser lenses62 and 63, so that reimaging positions on the light receiving portionsof the AF sensors are closer, as seen in FIG. 9 compared to FIG. 10. Itshould be noted that this effect implies that the light receivingportions of the AF sensors can accordingly be disposed closer eachother.

For the purpose of verifying the effect of eccentricity of the condenserlenses 62 and 63, in FIG. 10, the condenser lenses 62 and 63 withouteccentricity are indicated. It is clearly understood that in FIG. 10that the area of the mirrors 21 and 22 is larger than that of FIG. 9.Furthermore, the light receiving portions 42, 45, and 44, 46 of the AFsensors are distantly disposed, so that the size of the module in whichthe reimaging optical system is contained is inevitably large.

Though the deflecting mechanism is explained with reference to FIG. 9,the effect of the deflecting mechanism is indicated only by theeccentricity of the condenser lenses 62 and 63, each of which correspondto the intermediate apertures 14 and 15. Further examples of thedeflecting mechanism are therefore indicated in FIG. 11(a) through FIG.11(c) and FIG. 12(a) through FIG. 12(c) in a similar manner as FIG. 5(a)through FIG. 5(d), FIG. 6(a) through FIG. 6(e), and FIG. 7(a) and FIG.7(b). The series of measures applied to the peripheral aperture 13 andthe intermediate aperture 15 are also applicable to the peripheral andthe intermediate apertures 12 and 14.

FIG. 11(a) shows an example where the condenser lens 63 does not have aneccentricity, i.e., no deflecting mechanism is provided. As explained,to take in a bundle of ray without vignetting, it is preferable for theintermediate and the peripheral apertures 15 and 13 to take in bundlesof rays from an area of the exit pupil of the photographing lens asclose as possible to the optical axis Ax of the photographing lens.

FIG. 11(b) shown an example of bundles of rays inclined toward theoptical axis Ax of the photographing lens. This example, however, causesthe light receiving portions 42 and 45 to be distant from the opticalaxis Ax, which inevitably makes the area occupied by the light receivingportions of the AF sensors larger.

FIG. 11(c) shows an example where prisms 80 are disposed behind each ofthe condenser lenses 62 and 65. It is clearly understood that thedirection of the bundles of rays are inclined toward the optical axis Axwhile the position of the light receiving portions 42 and 45 of the AFsensors is maintained as that of FIG. 11(a).

In addition to the above, FIG. 12(a) through FIG. 12(c) indicateexamples in which a distance between the light receiving portions 42 and45 of the AF sensors are shortened.

FIG. 12(a) shows an example that simply relocates the light receivingportion 42 towards the light receiving portion 45. This causes thebundle of ray taken in the intermediate aperture 15 to be too close tothe optical axis Ax of the photographing lens.

FIG. 12(b) shows an example to compensate for the above drawback. Theprism 80 is disposed behind condenser lens 62, so that the bundle ofrays passed through the intermediate aperture 15 is adequately inclinedwith respect to the optical axis Ax of the photographing lens, and thebundles of rays passing through the peripheral and the intermediateapertures 13 and 15 are maintained as those of FIG. 11(b) and FIG.11(c).

FIG. 12(c) further shows another example in which the prism 80 isdisposed behind the condenser lens 65 to deflect the bundle of raypassed through the peripheral aperture 13 towards the bundle of raypassed through the intermediate aperture 15, so that the light receivingportion 45 is disposed closer to the light receiving portion 42.

As can be understood from the above discussion, the deflecting mechanismmakes one bundle of rays passing through at least one of the aperturesto be close to anther bundle of ray passing through another aperture, sothat the light receiving portions of the AF sensors can be disposedclosely each other, and so that apertures formed in the sagittaldirection of the photographing lens can take in a bundle of rays from anarea of the exit pupil of the photographing lens close to the opticalaxis of the lens. Furthermore, according to the orientation changingmechanism, the apertures on the field mask can be formed in a differentorientation configuration than that of the light receiving portions ofthe AF sensors.

I claim:
 1. A focus detecting apparatus, comprising:a plurality of focus detecting zones disposed on a focal plane, said plurality of focus detecting zones being arranged in a first orientation configuration, said focus detecting zones allowing bundles of rays from a photographing lens to pass through; a plurality of condenser lenses disposed behind said focus detecting zones, each of said condenser lenses corresponding to each of said detecting zones; plural pairs of separator lenses for splitting images seen through said plurality of focus detecting zones; a sensor unit having multiple line sensors arranged in a second orientation configuration that differs from said first orientation configuration, said multiple line sensors being disposed on a reimaging plane for reimaging said split images, each of said line sensors corresponding to each of said plurality of focus detecting zones; deflecting means for deflecting a bundle of rays passing through at least one of said plurality of focus detecting zones to be close to another bundle of rays passing through another of said plurality of detecting zones while said first orientation configuration is maintained; and orientation changing means for changing an orientation configuration of said bundle of rays from said first orientation configuration passed through said plurality of focus detecting zones into said second orientation configuration, said changing means being positioned between said deflecting means and said separator lenses.
 2. The focus detecting apparatus according to claim 1, at least one of said plurality of focus detecting zones being arranged in a radial direction of said photographing lens and the remaining zones of said plurality of focus detecting zones being arranged in a sagittal direction of the photographing lens, said deflecting means deflecting a bundle of rays passing through at least one of said zones arranged in said sagital direction of the photographing lens to be close to a bundle of rays passing through said zone arranged in said radial direction of the photographing lens.
 3. The focus detecting apparatus according to claim 2, said deflecting means deflecting a bundle of rays passing through at least one of said zones in said sagittal direction of the photographing lens to be close to a bundle of rays passing through said zone arranged in said radial direction of the photographing lens.
 4. The focus detecting apparatus according to claim 2, said deflecting means making each of said bundles of rays passing through said zones arranged in said sagittal direction of the photographing lens incline toward an optical axis of the photographing lens.
 5. The focus detecting apparatus according to claim 2, said deflecting means making one of said bundles of rays passing through at least one of said zones arranged in said sagittal direction of the photographing lens, incline toward an optical axis of the photographing lens, said deflecting means making one of said bundles of rays passing through at least one of said zones arranged in said sagittal direction of the photographing lens incline toward a bundle of rays passing through said zone arranged in said radial direction of the photographing lens.
 6. The focus detecting apparatus according to claim 3, said orientation changing means comprising: two mirrors, each of said two mirrors reflecting bundles of rays passed through each of said zones arranged in said sagittal direction of the photographing lens, by 90 degrees to said line sensors corresponding to said zones arranged in said sagittal direction, so that said bundles of rays are incident on said line sensors; andone mirror which reflects said bundle of rays passed through said zone arranged in said radial direction of the photographing lens by 90 degrees to said line sensors corresponding to said zones arranged in said radial direction so that said bundle of rays is incident on said line sensors.
 7. The focus detecting apparatus according to claim 3, said deflecting means comprising an eccentricity provided on at least one surface of said condenser lens corresponding to said zones arranged in said sagittal direction of the photographing lens, said eccentricity being provided by deviating said condenser lens from an axis extending between a center of said zone and a center of a pair of said plural pairs of separator lenses.
 8. The focus detecting apparatus according to claim 3, said deflecting means comprising a prism disposed behind a condenser lens of said plurality of condenser lenses.
 9. The focus detecting apparatus according to claim 3, said deflecting means comprising a combination of a prism and an eccentricity of a condenser lens of said plurality of condenser lenses.
 10. The focus detecting apparatus according to claim 1,said plurality of focus detecting zones on said focal plane comprising a plurality of central focus detecting zone zones arranged in said radial direction of the photographing lens, a plurality of peripheral zones arranged in a sagittal direction of the photographing lens, and a plurality of intermediate zones arranged in said sagittal direction of the photographing lens; each or said plurality of intermediate zones being disposed between said plurality of central zones and adjacent ones of said plurality of peripheral zones; and said deflecting means being disposed between said plurality of focus detecting zones and said orientation changing means so that a bundle of rays passing through at least one of said plurality of peripheral zones is inclined towards a bundle of rays passing through one of said plurality of intermediate zones.
 11. The focus detecting apparatus according to claim 10, said deflecting means deflecting a bundle of rays passing through said at least one of intermediate focus detecting zones to be close to a bundle of rays passing through one of said peripheral focus detecting zones.
 12. The focus detecting apparatus according to claim 10, said deflecting means making said bundles of rays passing through said peripheral focus detecting zones and said intermediate focus detecting zones incline towards said optical axis of said photographing lens.
 13. The focus detecting apparatus according to claim 10, said deflecting means making said bundles of rays passing through said peripheral zones and said intermediate zones incline towards an optical axis of the photographing lens, said deflecting means making said bundles of rays passing through said peripheral zones incline toward said bundles of rays passing through said intermediate zones.
 14. The focus detecting apparatus according to claim 11, said deflecting means comprising a prism disposed behind said condenser lens, on which a bundle of rays passing through said intermediate zones is incident.
 15. The focus detecting apparatus according to claim 11, said orientation changing means comprising:one mirror, which reflects said bundles of rays passing through said plurality of said central focusing zones arranged in said radial direction of the photographing lens 90 degrees to said line sensors so that said bundles of rays are incident on said line sensors corresponding to said plurality of central zones; and two mirrors, each of which reflects each of said bundles of rays passing through said intermediate and peripheral zones arranged in said sagittal direction of the photographing lens 90 degrees to said line sensors corresponding to said intermediate and peripheral zones so that said bundles of rays are incident on said line sensors.
 16. The focus detecting apparatus according to claim 6, said multiple line sensors arranged in said second orientation configuration comprising a row of single CCD sensors.
 17. The focus detecting apparatus according to claim 15, said multiple line sensors comprising two rows of single CCD sensors, and one of said central zones arranged in said radial direction of said photographing lens, one of said intermediate zones arranged in said sagittal direction of said photographing lens, and one of said peripheral zones arranged in said sagittal direction correspond to one row of said two rows of said single CCD sensors, and another of said central zone, another of said intermediate zone, and another of said peripheral zones correspond to the other row of said two rows of said single CCD sensors.
 18. The focus detecting apparatus according to claim 1, wherein said first orientation configuration is H-shaped, and said second orientation configuration is line-shaped. 